Plate valve mechanism for fluid pressure tools



Dec. 22, 1931. E. w. STEVENS 1,837,799

PLATE VALVE MECHANISM FOR FLUID PRESSURE TOOLS Filed Dec. 7, 1929 Fig-1 L NZ Edward 14/ 676mm A TTORNE Y.

Patented Dec. 22, 1931 arts 'r TEs' PATENT was 1 EDWARD W. STEVENS, 013 DETROIT, IVII CI-IIGAN, ASSIGNOR TO CHICAGO PNEUI-eTATIC TOOL COMPANY, OF. YORK, Y., A CORPORATION OF NEW JERSEY PLATE VALVE mncnamsivr Fen. FLUID PRESSURE Toots Application filed December 7, 1929. Serial No. 412,334.

This invention relates to fluid actuated percussive tools and particularly hand held machines in which the piston reciprocates in the cylinder and is controlled by a fluid actuated distributing valve. In the present embodiment of the invention the piston is of the free moving hammer type and is adapted to strike a working toohbut by providing a shank or piston rod to the piston it maybe employed as a sand rammer or tamping tool and the like.

Theobjects of the invention are to improve the construction and operation of the auto matic distributing valve which in this instance controls only the inlet of live pressure fluid'to the cylinder. A free exhaust in the side of the cylinder is-controlled only by the piston and the valve itselfis an improvement on the so-called flap valve in whichthe flow or current of pressure fluid'in conjunction with the drop of pressurebeneath one end of the valve exerted against the otherend of the valve causes the valve to operate. In accord ance with this improved construction the valve is located rearwardly ofthe cylinder on a simple head block which is held in position by the handle or backhead.

The invention is illustrated in one of its preferred forms in the accompanying drawings in which:

Fig. 1 is a longitudinal sectional elevation of a chipping hammer;

Fig. 2 is a similar view with thepiston and valve in a different position; and v Fig. 3 is avertical fragmentary sectional view substantially on the line 3-3 of Fig. 9..

Referring to the drawings the backhead or handle A has the usual throttle mechanism and alive pressure fluid passage B leading to the valve chamber, and is secured to the cylinder C by threaded engagement or any other suitable method and within the backhead member A and rearwardly of the cylinder C is located the valve D and head block E upon which the washer shaped plate valve D works. As a means of keeping the valve centrally located on the head block E a tubular shaped member or band F is placed around the ext nded portion of the head block E that has the tapered valve seat, and as ameans of holding the valve down a retainer in the form of a small rod or shaft G is placed directly across and in line with the center axis of the valve seat and as a means of locating and holding the said retainer rod in proper relation to the valve seat recesses or grooves are cut on opposite sidesof the band F to receive the ends of the rod. A key or dowel keeps member F in proper relation with the head block E. a

The valve D is a thin circular disk of uniform thickness and diameter and has a hole in the center through which the live motive fluid passes. The valve disk oscillates on the axis of the head block E and is kept centrally located by the surrounding member F. Only sufficient clearance is provided between the periphery of the valve and the bore of' member F to prevent binding and permit free oscillation.

The head block E is provided with inlet ports H and V controlled only by the valve D. The inlet port H leads tothe rear end of the cylinder while the inlet port V communicates with the passage leading to the inlet port K at the forward end of the cylinder. Exhaust passages L in the cylinder communicate with the atmospheric exhaust ports M and with the exhaust ports N and N located approximately as shown. i

In the operation of the device letit be assumed that the piston O is at the forward end of the cylind er C and is in contact with the working tool P as indicated in Fig. 1 with the valve 1) also in the position indicated so that the live pressure fluid entering at the inlet B is exerting an equal pressure over the entire rear or top area of the valve D. The inlet port H being open to atmospheric pressure through the cylinder and exhaust ports N and M. the live air pressure on the opposite face of the valve causes it to tip down and close the said port H. Live air passes through the center opening in the valve and under it to the inlet port V thence through the duct J and port K into the forward piston chamber to drive the piston rearwardly. As piston O on its rearward movement uncovers the forward exhaust ports N a drop of pressure results beneath the valve sure beneath the valve, as

stroke the pressure will drop at the rear and V will build up at the forward end with sufficient pressure to tip the valve, and in that manner the cycle will repeat as the piston reciprocates.

The diameter of the hole in the valve D has an important relation to the angle of the valve seat and the area of the ports II and V. The reason for this is to permit the live air to flow from the inlet ports H and V with slightly more freedom than through the clearance space between the rim of the valve bore and the seat, thus permitting the incoming air tofollow or inv other words to produce a wire drawing effect with a drop in prespreviously described;

One of the important advantages of the present invention over known types of flat valves is that it will permit the use of one valve of standard shape and size for all tools. The valve is exceptionally easy and inexpensive to make since it is a simple disk of uniform thickness. This valve is fool proof in the sense that it does not require locating by dowels'and can be inserted either side up. Being a flat disk it slowly rotates when in operation and thus wears uniformly.

While'the invention has been herein disclosed in what is now considered to be a preferred form it is to be understood that it is not limited to the exact details thereof but covers all changes, modifications, and adaptations within the scope of the appended claims.

I claim as my invention:

1. In a fluid pressure tool having a reciprocating piston, valve mechanism for controlling the movements of the piston comprising a valve block having a valve recess and providing a seat tapered in opposite directions, said block havingrp'orts extending through said tapered seat portions, and a plate valve in said recess for controlling said ports, said valve having an unrestricted bore therethrough for passing motive fluid to said ports in alternation.

2. In a fluid pressure tool having a reciprocating piston, valve mechanism for controlling the movements of the piston comprising a valve block having a valve recess and providing a seat tapered in opposite directions, said block-having ports extending through said tapered seat portions, a plate valve in said recess for. controlling saidports,

said valve having an open bore therethrough' for passing motive fluid to said ports in alternation, and retainer means extending transversely of said block for maintaining said valve in said recess.

3. In a fluid pressure tool having a reciprocating piston, valve mechanism for controlling the. movements of the piston comprising a valve block having a valve recess and providing a seat tapered in opposite directions, said block having ports extending through said tapered seat portions, a plate valve in said recess for controlling said ports, said valve having a bore therethrough for passing motive fluid to said ports in alternation, and a central open retainer member extending across said block in line with the median of said tapered seat for maintaining said valve in said recess.

. i 4. In a fluid pressure tool having a recip- 'rocating piston, valve mechanism for controlling the movements'of the piston comprising a valve block having a valve recess and providing a seat tapered in opposite directions, said block having ports extending through'said tapered seat portions, a plate valve in said recess for controlling said ports, said valve having a bore therethrough for passing motive fluid to said ports in alternation, and a retainer rod extending across said block externally thereof and having its ends seated in recesses in the latter for maintaining said valve in operative position in said recess.

5. In a fluid pressure percussive tool having a cylinder with a piston reciprocable therein and a head with a motive fluid inlet secured to said cylinder, a valve block interposed between said cylinder and head comprising a seat member forming a closure for the end of the cylinder and providing semicircular seatstapered from a median line, said member having ports extending through said seats for directing motive fluid to opposite ends of said cylinder, and a plate valve in the form of .a washer having a central aperture mounted to oscillate on said median line to control said ports, the aperture in said valve being unrestricted for the passage of motive fluid to said ports.

6. In a fluid pressure percussive tool having a cylinder with a piston reciprocable therein and; a head with a motive fluid inlet secured to said cylinder, a valve block interposed between said cylinder and head comprising a seat member forming a closure for the end of the cylinder and providing semicircular seats tapered from a median line, said member having ports extending through said seats for directing motive fluid to opposite ends of said cylinder, an annular member inclosing said seats to deflne the valve chamber, and anannular plate valve within said chamber loosely fitting said last named member for oscillating movement on said median line to control said ports, the aperture in said valve serving to pass motive fluid to said ports.

7. In a fluid pressure percussive tool having a cylinder with a piston reciprocable therein and a head with a motive fluid inlet secured to said cylinder, a valve block interposed between said cylinder and head comprising a seat member forming a closure for the end of the cylinder and providing semicircular seats tapered from a median line, said member having ports extending through said seats for directing motive fluid to opposite ends of said cylinder, an annular memher in keyed and telescoping engagement with said seat member to definethe valve chamber, and an annular plate valve within said chamber loosely fitting said last named member for oscillating movement on said median line to control said ports, the aperture in said valve serving to pass motive fluid to said ports. 8. In a fluid pressure percussive tool having a cylinder with a piston reciprocable therein and a head with a motive fluid inlet secured to said cylinder, a valve block interposed between said cylinder and head comprising a seat member forming a closure for the end of the cylinder and providing semicircular seats tapered from a median line, said member having ports extending through said seats for directing motive fluid to opposite ends of said cylinder, a plate valve in the form of a washer mounted to oscillate on said median line to control said ports, said valve having an aperture in line with said inlet for passing motive fluid to said ports, and means in parallelism with said median line for retaining said valve in place.

9. In a fluid pressure percussive tool having a cylinder with a piston reciprocable therein and a head with a motive fluid inlet secured to said cylinder, a valve block interposed between said cylinder and head comprising a seat member forming a closure for the end of the cylinder and providing semicircular seats tapered from a median line, said member having ports extending through said seats for directing motive fluid to opposite ends of said cylinder, an annular member in keyed and telescoping engagement with said seat member to define the valve chamber, an annular plate valve within said chamber loosely fltting said last named member for oscillating movement on said median line to control said ports, the aperture in said valve serving to pass motive fluid to said ports, and means on said annular member for retaining said valve in operative position in said valve chamber.

10. In a fluid pressure percussive tool having a cylinder with a piston reciprocable therein and a head with a motive fluid inlet secured to said cylinder, a valve block interposed between said cylinder and head comprising a seat member forming a closure for the; end of thecylinder and providing semicircular seats tapered from a median line, said member having ports extending through said seats for directing motive fluid to opposite ends of said cylinder, an annular member in keyed and telescoping engagement with said seat member to define the valve chamber, an annular plate valve within said chamber loosely fitting said last named member for oscillating movement on saidmedian line to control said ports, the aperture in said valve servingto pass motive fluid to said ports, and means onrsaid annular member for retaining said valve in operative position in said valve chamber comprising a rod disposed in parallelism with said median line.

11. A fluid pressure percussive tool having a cylinder provided with one exhaust port communicating with atmosphere, a piston reciprocable in said cylinder and controlling said exhaust port, a head having a conduit for motive fluid secured to said head, a valve block forming a closure for said cylinder and clamped against the latter by said head, said block having a circular valve recess and providing valve seats therein tapered from a median line, said block having ports in said seats communicating with the opposite ends of said cylinder, an annular valve in said chamber for oscillatory movement on said line to control said ports, the aperture in the valve being free of restriction and of a size bearing a critical relation to the taper of said seats whereby when one of said seat ports uncovered by said valve is put in communication with atmosphere by said piston a drop in pressure under said valve will result tending to cause said valve to close said port.

12. A- valve assembly for fluid pressure tools comprising a valve block providing a circular valve recess having valve seats tapered in opposite directions from a median line, said block having ports in said seats, and an annular flat disk valve of uniform thickness loosely fitting said recess for oscillatory movement on said median line to engage said seats and to control said ports in alternation, said valve being free to rotate in said recess.

13. In a valve assembly for fluid pressure tools, a block comprising a seat member and another member in interengaged relation to provide a valve recess, said seat member providing seats tapered oppositely from a median line and ports in said seats, a plate valve in said recess for controlling said ports, and a retainer member on said other member extending across said recess in parallelism with said median line, said retainer member loosely engaging the exterior of said valve to leave the latter free for rotary movement in said recess.

14. In a valve assembly for fluid pressure tools, a block comprising a seat member and an annular member in interfltting keyed relation to provide a circular valve recess,*said seat member providing seatstapered oppositely from a median line and ports in said seats, aplate valve in the form of a Washer loosely fitting said annular member to permit oscillatory movement in said recess on said median line, said annular member havingaligned recesses remote from said seat member, and a retainer member seated in said aligned recesses and spanning said valve recess in substantial parallelism with said medianline, said retainer member loosely engaging the face of said valve remote from saidseats.

Signed by me at Detroit, in the county of Wayne and State of Michigan, this 5th day of December, 1929;

. EDWARD W. STEVENS.

' CERTIFICATE OF CORRECTION.

Patent No. 1,837,799. Granted December 22, 1931, to

EDWARD W. STEVENS.

It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction as follows: Page 2, line 80, claim 3, strike out the words "central open" and insert same to follow the article "a" in line 78, of same claim; and that the said Letters Patent should be read with this correction therein that the same may conform to the record of the case in the Patent Office.

Signed and sealed this 9th day of February, A. D. 1932.

M. J. Moore,

(Seal) Acting Commissioner of Patents. 

